During descent to the surface over land in the northern hemisphere, what change in wind direction and speed will a pilot typically experience?

During descent to the surface over land in the northern hemisphere, what change in wind direction and speed will a pilot typically experience?

• A. Veering ca. 10 degrees, speed reduced by ca. 30%
• B. Backing ca. 30 degrees, speed reduced by ca. 50%
• C. Veering ca. 30 degrees, speed reduced by ca. 50%
• D. Backing ca. 10 degrees, speed reduced by ca. 30%

Answer: (B)

When an aircraft descends to the surface over land in the northern hemisphere, it generally experiences a backing of the wind direction. This change is associated with a decrease in wind speed as the aircraft approaches the ground. More specifically, backing refers to the wind changing direction in a counterclockwise manner, typical of the effects of surface friction and the change in airflow patterns as the altitude decreases. The significant reduction in wind speed, about 50%, occurs due to this frictional drag as the aircraft gets closer to the surface. The air slows down as it interacts with the terrain, resulting in a lower speed experienced by the aircraft. This is particularly relevant for pilots to understand, as these changes can affect both the aircraft's performance and handling characteristics during the final approach and landing phase. In summary, during a descent over land in the northern hemisphere, the typical phenomena include a noticeable backing of the wind direction and a substantial decrease in wind speed, which aligns with the provided correct answer.

When an aircraft descends to the surface over land in the northern hemisphere, it generally experiences a backing of the wind direction. This change is associated with a decrease in wind speed as the aircraft approaches the ground. More specifically, backing refers to the wind changing direction in a counterclockwise manner, typical of the effects of surface friction and the change in airflow patterns as the altitude decreases.

The significant reduction in wind speed, about 50%, occurs due to this frictional drag as the aircraft gets closer to the surface. The air slows down as it interacts with the terrain, resulting in a lower speed experienced by the aircraft. This is particularly relevant for pilots to understand, as these changes can affect both the aircraft's performance and handling characteristics during the final approach and landing phase.

In summary, during a descent over land in the northern hemisphere, the typical phenomena include a noticeable backing of the wind direction and a substantial decrease in wind speed, which aligns with the provided correct answer.